Building A Rocket Engine From Scratch

May 5, 2024 by Al Williams 14 Comments

There is a reason building a rocket engine is harder than most things you want to build. If you are building, say, a car, your goal is to not have it explode. If you are building a bomb, you want that to explode. But a rocket engine needs to explode just enough and not a bit more. That’s tough, as [Ryan Kuhn] discovered. He’s behind ABL’s E2 rocket, a LOX/kerosene engine for small vehicle launches. You can catch a video of the engine’s qualification tests below.

[Ryan] shares many of the problems encountered from many problems, each requiring finetuning of the design. True, there are plenty of publicly available NASA documents about what works and doesn’t work for rocket engines, but that can only take you so far. You can’t learn to bowl by reading about bowling, and you can’t design a successful rocket on paper just by reading about what others have done.

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Welcome Back, Voyager

April 27, 2024 by Elliot Williams 59 Comments

In what is probably the longest-distance tech support operation in history, the Voyager mission team succeeded in hacking their way around some defective memory and convincing their space probe to send sensor data back to earth again. And for the record, Voyager is a 46-year old system at a distance of now 24 billion kilometers, 22.5 light-hours, from the earth.

While the time delay that distance implies must have made for quite a tense couple days of waiting between sending the patch and finding out if it worked, the age of the computers onboard probably actually helped, in a strange way. Because the code is old-school machine language, one absolutely has to know all the memory addresses where each subroutine starts and ends. You don’t call a function like do_something(); but rather by loading an address in memory and jumping to it.

This means that the ground crew, in principle, knows where every instruction lives. If they also knew where all of the busted memory cells were, it would be a “simple” programming exercise to jump around the bad bits, and re-write all of the subroutine calls accordingly if larger chunks had to be moved. By “simple”, I of course mean “incredibly high stakes, and you’d better make sure you’ve got it right the first time.”

In a way, it’s a fantastic testament to simpler systems that they were able to patch their code around the memory holes. Think about trying to do this with a modern operating system that uses address space layout randomization, for instance. Of course, the purpose there is to make hacking directly on the memory harder, and that’s the opposite of what you’d want in a space probe.

Nonetheless, it’s a testament to careful work and clever software hacking that they managed to get Voyager back online. May she send for another 46 years!

Photo Shows Real Spiders From Mars

April 27, 2024 by Jenny List 16 Comments

A cornerstone of early 1970s rock music culture was the British singer David Bowie in his Ziggy Stardust persona, along with his backing band the Spiders from Mars. You can tell that the PR department at the European Space Agency were beside themselves with glee at the opportunity to reference them when their Mars Express spacecraft snapped a picture of some of the planets surface structures which bear a passing resemblance to Earth-bound spiders. We can’t blame them, we’d have done the same.

While these spiders are definitely not arachnid in origin, they are no less interesting. Over the Martian winter there form layers of carbon dioxide ice, which turn to gas under the influence of the Sun. This gas becomes trapped underneath layers of ice, until it forms sufficient pressure to burst through and escape. In doing so it brings up dark dust which settles along fissures in the ice, leading to the spider-like patterns when viewed from orbit.

So no life on Mars then, at least as yet. But it’s an interesting observation, and another little piece in the puzzle of understanding our planetary neighbor, as well as an excuse for a classic rock earworm. Meanwhile, this isn’t the first time we’ve reported on the ESA Mars probes.

The Myth Of Propellantless Space Propulsion Refuses To Die

April 25, 2024 by Maya Posch 106 Comments

In a Universe ruled by the harsh and unyielding laws of Physics, it’s often tempting to dream of mechanisms which defy these rigid restrictions. Although over the past hundred years we have made astounding progress in uncovering ways to work within these restrictions — including splitting and fusing atoms to liberate immense amounts of energy — there are those who dream of making reality a bit more magical. The concept of asymmetrical electrostatic propulsion is a major player here, with the EmDrive the infamous example. More recently [Dr. Charles Buhler] proposed trying it again, as part of his company Exodus Propulsion Technologies.

This slide from Dr. Buhler’s APEC presentation shows the custom-made vacuum chamber built to test their propellantless Propulsion drive in a simulated space environment. Image Credit: Exodus Propulsion Technologies, Buhler, et al.

The problem with such propellantless space propulsion proposals is that they violate the core what we know about the physical rules, such as the conclusion by Newton that for any action there has to be an opposite reaction. If you induce an electrostatic field or whatever in some kind of device, you’d expect any kind of force (‘thrust’) this creates to act in all directions equally, ergo for thrust to exist, it has to push on something in the other direction. Rocket and ion engines (thrusters) solve this by using propellant that create the reaction mass.

The EmDrive was firmly disproven 2021 by [M. Tajmar] and colleagues in their paper titled High-accuracy thrust measurements of the EMDrive and elimination of false-positive effects as published in CEAS Space Journal, which had the researchers isolate the EmDrive from all possible outside influences. Since the reported thrust was on the level of a merest fraction of a Newton, even the impact from lighting in a room and body heat from the researchers can throw off the results, not to mention the heat developed from a microwave emitter as used in the EmDrive.

Meanwhile True Believers flock to the ‘Alt Propulsion Engineering Conference’ (APEC), as no self-respecting conference or scientific paper will accept such wishful claims. In the case of [Buhler], he claims that their new-and-improved EmDrive shows a force of 10 mN in a ‘stacked system’, yet no credible paper on the experiments can be found other than APEC presentations. Until their prototype is tested the way the EmDrive was tested by [M. Tajmar] et al., it seems fair to assume that the rules of physics as we know them today remain firmly intact.

NASA’s Voyager 1 Resumes Sending Engineering Updates To Earth

April 22, 2024 by Maya Posch 29 Comments

After many tense months, it seems that thanks to a gaggle of brilliant engineering talent and a lucky break the Voyager 1 spacecraft is once more back in action. Confirmation came on April 20th, when Voyager 1 transmitted its first data since it fell silent on November 14 2023. As previously suspected, the issue was a defective memory chip in the flight data system (FDS), which among other things is responsible for preparing the data it receives from other systems before it is transmitted back to Earth. As at this point in time Voyager 1 is at an approximate 24 billion kilometers distance, this made for a few tense days for those involved.

The firmware patch that got sent over on April 18th contained an initial test to validate the theory, moving the code responsible for the engineering data packaging to a new spot in the FDS memory. If the theory was correct, this should mean that this time the correct data should be sent back from Voyager. Twice a 22.5 hour trip and change through Deep Space and back later on April 20th the team was ecstatic to see what they had hoped for.

With this initial test successful, the team can now move on to moving the remaining code away from the faulty memory after which regular science operations should resume, and giving the plucky spacecraft a new lease on life at the still tender age of 46.

NASA’s Ingenuity Mars Helicopter Transitions Into Stationary Testbed

April 19, 2024 by Maya Posch 22 Comments

On April 16th NASA announced the formal end to Ingenuity’s days as the first ever Martian helicopter, following its 72nd and final flight mission in January. This flight ended with a rough landing during which the helicopter’s blades got damaged and separated, leaving the plucky flying machine with its wings clipped. During the final meet-up of the Mars Helicopter Team there was cake, but none for Ingenuity as its latest data set was reviewed by the team from 304 million kilometers away. This data confirms the latest software patch allows it to work stand-alone as a data collection platform.

With these latest software changes, Ingenuity will wake up daily, activate its computers and perform a self-check of all its components before collecting sensor data and images. The main goal of this is to collect long-term performance data on the helicopter’s systems, with enough onboard memory to allow for measurements to be stored for around 20 years. This means that although the Perseverance rover will have to trundle on without its flying mission buddy, one day in the future another rover, helicopter or primate will presumably drop by to either communicate with Ingenuity if it’s still alive, or harvest its memory unit for data retrieval.

Thanks to [Mark Stevens] for the tip.

Chandra X-ray Observatory Threatened By Budget Cuts

April 10, 2024 by Tom Nardi 39 Comments

Launched aboard the Space Shuttle Columbia in July of 1999, the Chandra X-ray Observatory is the most capable space telescope of its kind. As of this writing, the spacecraft is in good health and is returning valuable scientific data. It’s currently in an orbit that extends at its highest point to nearly one-third the distance to the Moon, which gives it an ideal vantage point from which to make its observations, and won’t reenter the Earth’s atmosphere for hundreds if not thousands of years.

Yet despite this rosy report card, Chandra’s future is anything but certain. Faced with the impossible task of funding all of its scientific missions with the relative pittance they’re allocated from the federal government, NASA has signaled its intent to wind down the space telescope’s operations over the next several years. According to their latest budget request, the agency wants to slash the program’s $41 million budget nearly in half for 2026. Funding would remain stable at that point for the next two years, but in 2029, the money set aside for Chandra would be dropped to just $5.2 million.

Drastically reducing Chandra’s budget by the end of the decade wouldn’t be so unexpected if its successor was due to come online in a similar time frame. Indeed, it would almost be expected. But despite being considered a high scientific priority, the x-ray observatory intended to replace Chandra isn’t even off the drawing board yet. The 2019 concept study report for what NASA is currently calling the Lynx X-ray Observatory estimates a launch date in the mid-2030s at the absolute earliest, pointing out that several of the key components of the proposed telescope still need several years of development before they’ll reach the necessary Technology Readiness Level (TRL) for such a high profile mission.

With its replacement for this uniquely capable space telescope decades away even by the most optimistic of estimates, the potential early retirement of the Chandra X-ray Observatory has many researchers concerned about the gap it will leave in our ability to study the cosmos.

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